1. Field of the Invention
The present invention relates to an apparatus for and a method of detecting the accumulated position of a radioisotope (hereinafter referred to as xe2x80x9cRIxe2x80x9d), i.e., the position of a radiation source, administered or injected into an examinee, and displaying the detected position on a light-emitting element assembly or a display device.
2. Description of the Related Art
For detecting the position of an RI administered or injected into an examinee, it has heretofore been customary for the operator to scan the examinee with a gamma probe (small-size gamma-ray detector), which comprises a scintillator and a PMT (photomultiplier tube) and has a detecting surface having a diameter ranging from 5 to 10 mm, held by hand, and determine the position where the detected electric output signal or detected sound is of a maximum level as the accumulated position of the RI.
The conventional process relies upon the operator""s senses to look for the position where the detected electric output signal or detected sound, which is converted from the detected electric output signal, is of a maximum level. Therefore, the process is disadvantageous in that the examinee often needs to be scanned on a trial-and-error basis, and, because the detecting surface is small as its diameter ranges from 5 to 10 mm, it takes the operator a considerable period of time until the accumulated position of the RI, i.e., the position of the radiation source, is detected.
In addition, since the gamma probe has only one radiation-to-electric conversion element or pixel, the process is unable to identify the accumulated position of the RI accurately even when it is detected.
The gamma probe with only one radiation-to-electric conversion element fails to meet a demand for the observation of an accumulated distribution of the RI on the examinee.
The PMT of the gamma probe is required to be operated under a high voltage and hence needs a large drive circuit. While the gamma probe itself may be of a relatively small size, the power supply device including the drive circuit for energizing the probe is large in size, and cannot easily be handled in use.
It is therefore an object of the present invention to provide a radiation source detecting apparatus which is of a simple arrangement capable of displaying an accumulated distribution of an RI.
Another object of the present invention is to provide a radiation source detecting apparatus which is capable of detecting the accumulated position of an RI reliably within a short period of time, and which can easily be handled in use.
Still another object of the present invention is to provide a radiation source detecting apparatus which is capable of rendering a distributed image of an RI on a display device or the like.
Yet another object of the present invention is to provide a radiation source detecting method which is capable of detecting the accumulated position of an RI reliably within a short period of time.
According to the present invention, a radiation emitted from a radiation source in an examinee is detected by an area sensor having a plurality of detecting elements, a distribution of the radiation source is detected by a signal processor based on signals outputted from the detecting elements, and the determined distribution of the radiation source is displayed by an image display unit. Therefore, the operator can recognize the distribution of the radiation source in the examinee from the displayed image.
According to the present invention, furthermore, when an examinee having a radiation source for emitting a radiation is scanned by an area sensor having a plurality of detecting elements, a position/direction display unit displays a pattern indicative of a position/direction of the radiation source which is determined by a signal processor based on signals outputted from the detecting elements. By operating the area sensor according to the displayed pattern, the operator can recognize the position of the radiation source, i.e., the accumulated position of a radioisotope in the examinee, reliably within a short period of time.
The display unit may display the determined distribution and/or position/direction of the radiation source. The operator can recognize the accumulated position of the radioisotope in the examinee reliably within a short period of time, and can also recognize the distribution of the radiation source in the examinee at the same time.
According to the present invention, furthermore, when an examinee is scanned with an area sensor disposed in a portion of a main unit having a prismatic shape and having a plurality of detecting elements, a display unit disposed in another portion of the main unit displays the determined distribution and/or position/direction of the radiation source which is determined by a signal processor based on signals outputted from the detecting elements. By operating the area sensor according to the displayed distribution and/or position/direction of the radiation source, the operator can recognize the position of the radiation source, i.e., the accumulated position of a radioisotope in the examinee, reliably within a short period of time, and also recognize the distribution of the radiation source in the examinee at the same time.
The display unit may comprise a single display unit including a display area for displaying the distribution of the radiation source and a display area for displaying the position/direction of the radiation source. Accordingly, the display unit can be produced inexpensively.
The display areas may be disposed in different positions or suitable members may be used as the respective display areas. For example, light-emitting diodes may be used as the display area for displaying the position/direction of the radiation source, and a liquid crystal display unit may be used as the display area for displaying the distribution of the radiation source. The liquid crystal display unit can easily display the intensity of the distribution, and the light-emitting diodes can clearly indicate the position/direction of the radiation source. If the position/direction display unit comprises a plurality of display areas for displaying the position/direction of the radiation source, then the operator can easily know the position/direction of the radiation source from a display on a certain one of the display areas.
If the display areas comprise arrow indicators disposed in a radial pattern, then the operator can easily know the position/direction of the radiation source from the orientation of one of the arrow indicators which is turned on.
The signal processor may comprise means for controlling flickering intervals of the display areas depending on the determined position/direction of the radiation source, or means for controlling displayed luminance levels of the display areas depending on the determined position/direction of the radiation source. These means allow the operator to visually recognize quickly whether the area sensor is approaching the position of the radiation source or not.
According to the present invention, there is also provided an apparatus for detecting a radiation source, comprising an area sensor having a plurality of detecting elements for detecting a radiation emitted from a radiation source in an examinee, a signal processor for processing signals outputted from the detecting elements into an audio signal, and audio output means for outputting sound and/or voice sound based on the audio signal from the signal processor, the signal processor comprising means for controlling the audio output means to generate sound and/or voice sound indicative of a position/direction of the radiation source.
With the above arrangement, since the position/direction of the radiation source is indicated by sound and/or voice sound, the operator can recognize the radiation source through the auditory sense.
The sound indicative of the position/direction of the radiation source may comprise a sound having a predetermined intensity and/or a predetermined frequency.
The voice sound indicative of the position/direction of the radiation source may comprise a voice sound representing the direction of a time on an analog clock whose center is regarded as the center of the area sensor.
Each of the detecting elements may comprise a CdTe or a CdZnTe semiconductor detecting element.
According to the present invention, there is further provided an apparatus for detecting a radiation source, comprising an area sensor having a plurality of radiation detecting elements, as many memories as the number of the radiation detecting elements, for storing respective output signals from the radiation detecting elements, and a signal processor for reading the output signals of the radiation detecting elements from the memory and processing the read output signals, the signal processor comprising means for combining a predetermined number of output signals or all output signals from the radiation detecting elements and outputting an image and/or audio signal based on the combined output signals.
Since the radiation detected in a small area can be displayed in a wide area or outputted as an audio signal, the operator can easily recognize the radiation source.
The detecting elements should preferably comprise nxc3x97m (n, m represent at least 2) detecting elements.
According to the present invention, there is also provided a method of detecting the position of a radiation source with an area sensor having a plurality of radiation detecting elements which provide a radiation detecting surface, comprising the steps of combining a predetermined number of output signals from the radiation detecting elements to cause the area sensor to function as a reduced number of radiation detecting elements without changing the area of the radiation detecting surface, combining a progressively reduced number of output signals from the radiation detecting elements to cause the area sensor to function as a progressively increased number of radiation detecting elements without changing the area of the radiation detecting surface, and finally, causing the area sensor to function as the plurality of radiation detecting elements.
Even if the radiation source is detected in a small area in the radiation detecting area of the area sensor, since the small area is one of the divided areas of the radiation detecting area of the area sensor, it is easy for the operator to specify the position of the radiation source.
All output signals from the radiation detecting elements may be combined to cause the area sensor to function as a single radiation detecting element without changing the area of the radiation detecting surface. This process allows the operator to recognize the presence of the radiation source quickly.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.